MX2011010194A - Method of signaling particular types of resource elements in a wireless communication system. - Google Patents

Abstract

A method of signaling particular types of resource elements in a wireless communication system is disclosed. The method can include, at a wireless terminal, receiving (610) a message providing information of a set of allocated resource elements carrying data intended for the wireless terminal. The method can include receiving (620) an indication corresponding to a resource element of a particular type within the set of allocated resource elements. The method can include decoding (630) resource elements that carry data intended for the wireless terminal based on the message providing information and based on the indication.

Description

METHOD OF SIGNALING PARTICULAR TYPES OF ELEMENTS OF RESOURCE IN A WIRELESS COMMUNICATION SYSTEM FIELD OF THE INVENTION The present disclosure generally relates to wireless communications and more particularly to signaling data mapping in a multiplexed orthogonal frequency division (OFDM) wireless communication system.

BACKGROUND OF THE INVENTION In OFDM wireless communication systems, a single OFDM symbol consists of multiple sub-bearers in frequency. The modulation symbols are assigned directly on these sub-bearers. Some of the sub-bearers may be reserved for reference symbols / pilots to assist in demodulation in the user's equipment (ÜE). In addition, all available sub-bearers can be subsequently divided into sets or groups of sub-bearers for assignment to users with reduced signaling saturation.

In typical systems based on OFDM such as the Long Term Evolution (LTE) of Society Project 3rd Generation (3GPP), a block of 14 consecutive OFD symbols is referred to as a sub-frame. Each subcarrier position in each of the OFDM symbols is referred to as a resource element (RE), since an individual data modulation symbol can be assigned to a resource element of this type. A resource block (RB) is defined as a block of REs composed of a set of 12 consecutive sub-carrier positions in frequency and 7 symbols in a slot. Each sub-frame of two slots, and therefore 14 symbols. A minimum resource unit assigned to a user consists of the two RBs corresponding to two slots in a sub-frame for a total of 2x12x7 RE.

Some REs in the RB can be reserved for channel control functions, whose positions are known to the UE. The description refers more specifically to the data carrier potion of the RB. This is, for example, referred to as Shared Physical Data Channel (PDSCH) in LTE version 8. Mentions of RE in the other documents are referred to in RE in such data carrying portions of the BRs.

Some REs in an RB are reserved for reference symbols (RS) (also referred to as pilots) to, assist in the demodulation and other measures in the EU. These reference symbols, as defined in LTE version 8, can be further divided into two types. The first type are specific cell-specific reference (CRS) symbols, which are specific cell and "common" for all users, and are transmitted to all RBs. The CRS may or may not correspond to the current physical antenna of the transmitter, but the CRS is associated with one or more antenna "ports", whether physical or virtual.

The second type are symbols specific to the user or dedicated reference (DRS), which are specific to the user and therefore applicable only to that user, and located in the RB assigned to that user. In addition, the DRSs typically correspond to "pre-coded" or beam-shaped RSs, which can be used directly by a user for the demodulation of the data streams.

The position of the reference symbols is known for the user equipment of higher layer configurations. For example, depending on the number of antenna ports as configured by a transmission unit, a user equipment knows the position of all the corresponding reference symbols with all the antenna ports configured. As another example, when a user equipment is instructed to use DRS, the user also knows the DRS positions that may depend on the user identification.

The data symbols determined for a user in their designated RBs are mapped to the remaining RE set after providing the reference symbols. There is no ambiguity in data mapping between the user equipment and the transmission unit once the RS positions are clear.

In a future migration of a system, user-specific RSs can be used with advanced modes of multiple inputs and multiple outputs (MIMO) such as coordinated multi-point transmission (CoMP) and multi-user MIMO (MU) modes. MIMO schemes of multiple users refer to MIMO schemes where data is transmitted simultaneously to more than one user from the same set of RBs. A coordinated scheme of multiple points is a scheme in which data is transmitted to one or more users through coordinated planning and / or joint transmission of one or more points. of transmission. It is clear in such a case, that a user assignment may have to support reference symbols that may correspond to other users and / or other transmission points.

On the other hand, the advantage of using DRS for demodulation in the user equipment has two main advantages. Current transmission mode details, such as number of users, number and identity of transmission points, etc., should not be signaled to a user, provided that the user can reconstruct the channel based on the DRS. In addition, this allows more dynamic changes to the transmission modes without the need to configure semi-statically by the upper layers, since a user should not be alerted about such explicit configurations.

However, due to the obligation of transmission assistance points in a CoMP transmission or provisioning reference symbols for other uses in a MU transmission, support for additional reference symbols may be required. There is a need for a method of signaling a particular type of resource element in a wireless communication system.

SUMMARY OF THE INVENTION A method of signaling particular types of resource elements in a wireless communication system is described. The method may include, in a wireless terminal, receiving (610) a message that provides information of a set of assigned resource elements carrying data directed to the wireless terminal. The method may include receiving (620) an indication corresponding to the resource element of a particular type within the set of assigned resource elements. The method may include decoding (630) resource elements that carry data directed to the wireless terminal based on the message providing information and based on the indication.

BRIEF DESCRIPTION OF THE FIGURES The various aspects, features and advantages of the invention will be more fully apparent to those of ordinary skill in the art with careful consideration of the following detailed description with the accompanying drawings described above. The drawings can be simplified for clarity and are not necessarily to scale.

Figure 1 is an exemplary illustration of a wireless communication system according to a possible embodiment; Figure 2 is a schematic block diagram of a wireless communication unit according to a possible mode; Figure 3 is an exemplary illustration of allocation of resources to different users in an OFDM communication system according to a possible mode; Figure 4 is an illustration of a resource block (RB) according to the specification of LTE version 8 with common RS (CRS) and dedicated RS (DRS); Figure 5 is an illustration of a resource block (RB) according to the LTE specification version 8 with reference symbols and RE of a particular type; Figure 6 is a flow diagram of an operation mode in the user equipment (UE); Figure 7 is a flow diagram of an operation mode in the base unit; Figure 8 is an illustration of coordinated multiple point operation mode (Co P) with reference symbols RE and an example of RE of a particular type; Y Figures 9A and 9B are an illustration of multi-user operation mode (MU) with the reference symbol RE and an example of RE of a particular type.

DETAILED DESCRIPTION OF THE INVENTION The modes provide a method of signaling particular types of resource elements in a wireless communication system. The method may include, in a wireless terminal, receiving a message with information from a set of assigned resource elements carrying data assigned to the wireless terminal. The method may include receiving an indication corresponding to a resource element of a particular type within the set of assigned resource elements. The method may include decoding resource elements that carry data assigned to the wireless terminal based on the message providing information and based on the indication.

Modalities provide a method of signaling particular types of resource elements in a wireless communication system. The method can signal mapping of data resource element. The method may include transmitting a message that provides information from a set of resource elements that carry data assigned to a wireless terminal. The method may include transmitting an indication in an orthogonal frequency division multiplexer system, wherein the indication corresponds to a resource element of a particular type within the set of assigned resource elements. The method may include mapping data modulation symbols to the set of resource elements allocated based on the indication.

Modalities provide a wireless terminal. The wireless terminal may include a transceiver configured to receive a message that provides information of a set of assigned resource elements carrying data directed to the wireless terminal and configured to receive an indication corresponding to a resource element of a particular type within the set of assigned resource elements. The wireless terminal may include a processor coupled to the transceiver, with the processor configured to control operations of the wireless terminal, with the processor configured to decode resource elements carrying data directed to the wireless terminal based on the message providing information and on the basis of to the indication.

Additional features and advantages of the invention will be detailed in the subsequent description, and in part will be obvious from the description or may be learned by practice of the invention. The features and advantages of the invention can be realized and obtained by means of the instruments and combinations particularly pointed out in the appended claims. These and other features of the present invention will be more apparent from the following description and appended claims, can be learned from the practice of the invention as described herein.

Various embodiments of the invention are discussed in detail below. While specific implementations are discussed, it should be understood that this is done for illustration purposes only. A person skilled in the relevant art will recognize that other components and configurations can be used without departing from the spirit and scope of the invention.

The present invention comprises a variety of embodiments, such as a method, an apparatus, and an electronic device, and other embodiments that relate to the basic concepts of the invention. The electronic device can be any computer configuration, mobile device or other wireless communication device.

In Figure 1, a wireless communication system 100 may include one or more units of fixed base infrastructure 101, 102 that form a distributed network in a geographic region to serve remote units. A base unit 101 may also be referred to as access point, access terminal, base, base station, Node-B, Node e B, Home node B, Node e Home B, relay node, or by other technology used in the art . The base unit or units 101, 102 may comprise one or more transmitters for downstream transmissions and one or more receivers for receiving upstream transmissions. Base units 101, 102 are generally part of a radio access network that includes one or more communicatively coupled controllers with one or more corresponding base units. The access network is generally coupled in a communicative way with other networks, such as the internet and public telephone networks, among others. These and other nuclear access elements and networks are not illustrated but are well known to those of ordinary skill in the art.

In Figure 1, the base unit (s) can serve a number of remote units 103, 104, 105, 106, 107 within a corresponding service area, eg, a cell or a cell sector, by a communication link. Wireless The remote units 103, 104, 105, 106, 107 can also be referred to as units subscribers, mobiles, mobile stations, user terminals, subscriber stations, user equipment (UE), user terminals, wireless communication devices, or by other terminology used in the art. The remote units 103, 104, 105, 06, 107 may include one or more transmitters and one or more receivers. In Figure 1, the base unit 101 can transmit downlink communication signals to serve the remote units 103, 105, 107 in time and / or frequency and / or spatial domain. The remote units 103, 105, 107 can communicate with the base unit 101 by means of uplink communication signals. A remote unit 104, 106 may communicate with the base unit 102 and / or base unit 101.? Sometimes the base unit 101 is referred to as a service cell, or connected or anchor for the remote units 103, 105, 107 and correspondingly the base unit 102 is referred to as an anchor cell for the remote units 104, 106. The remote units 103, 104, 105, 106, 107 may have full duplex (FD) or half duplex (HD) transceivers. The medium duplex transceivers do not transmit and receive simultaneously and the full duplex terminals do. The remote units can communicate with the base units by means of a relay node. Conventionally, a single point operation is when an anchor base unit (for example, 101) transmits data to remote units (for example, 103, 105, 107 here) served by this. In a multi-user scheme, such a base unit 101 can transmit data simultaneously over the air and in the same set of RE / RB to two or more users 10, 105, 107. In operation of multiple coordinate points (CoMP), two or more adjacent base units 101, 10 can simultaneously transmit to one or more units 103, 104, 105, 106, 107 by coordinating data to be transmitted to the individual users and taking into account information related to the interference channel. In such a case, a remote unit exchanges control information with its base anchor unit, but may receive transmissions from other base units. It may be partially or totally uninformed from (or blind to) the exact details / parameters of such controlled transmissions.

In one implementation, the wireless communication system can comply with the long-term evolution protocol (LTE) of the Universal Mobile Telecommunications System (UMTS) of the Third Generation Partnership Project, also referred to as 3GPP LTE terrestrial radio access ( EUTRA) of evolved universal mobile telecommunications system version 8 (Rel-8) or of later generations (for example, version 10 or advanced LTE), in where the base unit 101 can transmit using an orthogonal frequency division multiplexer modulation scheme (OFDM) in a downward manner and terminals 103, 104 can transmit upwardly using a single-carrier frequency division multiple access scheme (SC-FDMA ). More generally, however, the wireless communication system 100 can implement another open or proprietary communication protocol, for example iMAX, among others.

In Figure 2, a wireless communication unit or terminal 200 may include a controller / processor 210 communicatively coupled to a memory 21, a database interface 214, a transceiver 216, and an input / output device interface. (I / O) 218 connected through a bus 220 system.

The wireless communication unit 200 can be implemented as a base unit or a remote unit and can comply with the protocol of the wireless communication system within which it operates, such as, for example, the 3GPP LTE Rel-8 protocol or later generation discussed previously. In Figure 2, the controller / processor 210 can be implemented as any programmed processor. However, the functionality described here can be implemented also in a general purpose or special purpose computer, a microprocessor or programmed microcontroller, peripheral integrated circuit elements, a specific integrated circuit to the application or other integrated circuits, electronic logic circuits / hardware, such as a discrete integrated circuit, a device programmable logic, such as a programmable logic array, access matrix with programmable field, or the like. In Figure 2, memory 212 may include volatile and non-volatile data storage, including one or more electrical, magnetic or optical memories such as random access memories (RAM), cache, hard disk, read-only memory (ROM) , firmware, or other memory device. The memory 212 may have a cache to accelerate access to specific data. Data may be stored in memory 212 or in a separate database. The interface 214 can be used by the controller / processor 212 to access the database. The transceiver 216 may be able to communicate with user terminals and base stations complying with the wireless communication protocol imp.lementado. In some implementations, for example, where the communication unit 200 is implemented as the user terminal 103, the wireless communication unit 200 may include an I / O device interface 218 that is connected to one or more input devices that may include a keyboard, mouse, monitor or touch screen operated with pen or finger, speech recognition device, or any other device that accepts input. The device interface 1/0 218 can also be connected to one or more output devices, such as monitor, printer, disk slot, speakers, or any other device provided for data output.

In operation, the transceiver 216 may receive a message that provides information of a set of resource elements carrying data for the wireless terminal 200. The transceiver 216 may receive an indication corresponding to a resource element of a particular type within a set of assigned resource elements. The processor 210 can control operations of the wireless terminal 200. The processor 210 can decode resource elements that carry data directed to the wireless terminal 200 based on the message providing information and based on the indication.

Referring to Figure 1, the network base station 101 may have a set of physical antennas 108 for making a data transmission to the devices 103, 105, 107. A network base station 101 may coordinate with one or more stations. of network base 102 to do the transmission of data. A data transmission can be the act of sending data, regardless of the type of data or the form of transmission. A data transmission may comprise one or more streams of data via one or more effective channels. An antenna port may be associated with a current or observable effective channel to an UE 103 device. A physical antenna 108 may directly map to an individual antenna port, wherein an antenna port corresponds to a physical antenna. Alternatively, a set or subset of physical antennas 108, or array of antennas 108, may be assigned to one or more antenna ports after applying complex weights, a cyclic delay, or both to the signal on each physical antenna 108. The set of physical antennas 108 may have antennas of a single base station 101 or of multiple base stations. The weights can be set as an antenna virtualization scheme, such as cyclic delay diversity (CDD). The associated pilots may be different or common to all UE devices 103, 104, 105, 106, 107. The procedure used to derive antenna ports from physical antennas 108 may be specific to a base station implementation 101 and transparent to the devices. UE 103, 104, 105, 106, 107.

In an orthogonal frequency division multiplexer (OFDM) system, the entire bandwidth can be divide into orthogonal sub-carriers. A frequency sub-carrier in a period of an OFDM symbol can be referred to as a resource element (RE). A set of OFDM symbols forms a subframe within which the base station 101 may assign a set of REs in real time and / or a frequency domain to each UE for data transmission. An example of a sub-frame in an OFDM system is shown in Figure 3 where the UEs 103, 105, and 107 are respectively located with a set of REs in that sub-frame. These positions may or may not be adjacent in the frequency domain. There may or may not be a resource block definition (RB) which is a set of contiguous (or even non-contiguous) subcarriers in frequency domain over a duration of several OFDM symbols. If RB is defined as a base unit of positioning, which is assumed in Figure 3, the allocation of resources can be in multiples of RB. Note that the assignment of RE to each UE may consist of multiple RBs that may or may not be adjacent to each other. In Figure 3, the assignment to UE 103 comprises 2 non-adjacent RBs (e.g., RB 306 and RB 310).

A UE typically receives a control message that provides information from a set of assigned REs that carry data symbols addressed to the UE. Such an assignment can be represented as an RB number together with their positions.

It is generally understood that for each UE within the position, there are typically non-carrier data carriers that are used as pilots or reference symbols (RS) whose positions are known to the UE. RS for UE are provided to estimate the channel for the purpose of data demodulation or some type of measurements as required to report back to the base station. As described above, there may be two types of RS: specific cell RS or CRS that are intended for use by all UEs in that cell and dedicated DRS or RS (i.e., user-specific) that are intended for use only by the particular EU.

In the frame structure example shown in Figure 3, a base station 101 may send reference symbols in both frequency and time domains to enable UEs 103, 105, and 107 to obtain channel knowledge in both domains for demodulation. The CRS 302 set can be spread over the entire bandwidth of the system to allow UEs 103, 105 and 107 to estimate the channel for the entire band. The set of CRS 302 can be spread over time, or frame so that all UEs served by the same base station can track the time variation of the channel. CRS are sent regardless of the UE number and its allocation.

In Figure 3, DRS 304 can also be sent to a particular UE 103 to obtain an effective channel that is only useful for data demodulation of that UE. Typically, the base station 101 may embed DRS 304 in the resource allocation regions specific to the user. It is necessary to point out that although both types of RS are shown in figure 3, these may or may not be present simultaneously. For example, there may be only DRS or only CRS present in the system. From the perspective of each EU, DRS may or may not be present. For example, UE 103 is assigned with DRS in its assigned RBs 306 and 310, while UE 105 is not assigned with any DRS.

More details are provided below on the function of CRS and DRS in an OFDM transmission, wherein the transmitter has multiple antennas and the receiver has at least one and typically more than one antenna. Common reference symbols or specific cell reference symbols (CRS) may be sent from the base station 101 addressed to all UE devices in the cell as mentioned above. The CRS pattern (for example, RS positions and their values) may differ from cell to cell, hence the term "specific cell", but may be used by all the UEs in the cell, hence the term "common". A UE device typically learns about the CRS pattern after acquiring knowledge of a number of identification ID of a cell. For example, in 3GPP LTE, CRS have a uniform separation with a start position in frequency domain with a deviation that depends on the cell ID. There are three possible deviation values where the deviation is relative to the first RE in a BR.

In the case of multiple transmit antennas, the CRS can often be divided into a number of subsets, where each subset corresponds to a physical antenna port or a "virtual" antenna port where the virtualization process it can have a group of radial elements that transmit the same signal in a fixed way as explained above. In a virtualization process, the signal may be predetermined based on an implementation of base station 101, but in turn common and transparent to all UE devices. Again, in the 1TE specification example, CRS can be divided into 1.2 or 4 subsets corresponding to 1, 2 or 4 antenna ports whose number is announced by the eNB. Concrete physical antennas or radial elements may belong to one or more of said subsets used for virtualization. More generally, virtualization can be seen as mapping a set of radial elements to a set of common antenna ports, where such virtualization is common to all UEs.

? Unlike CRSs that are addressed to all UEs, dedicated reference symbols (DRS), or pilots specific to the user, they can address a particular UE. In a typical operation, a DRS can be embedded within a user mapping, such as sub-bearers or subbands or RBs as defined in LTE. A DRS may correspond to a "pre-coded" reference symbol, wherein the pre-coding may be performed in a manner similar to the pre-coding applied to data symbols.

The "pre-coding" operation is explained below. The base station transmits a signal giving weight to each antenna signal with a complex value, an operation referred to as pre-coding, which can be represented mathematically by the matrix equation: n Y = HVs which, when transmitting a data stream, or range-1, can be represented as: which, when transmitting two streams of data, or range-2, can be represented as: where yi ... and NR can be the data received in the reception antenna UE # 1 to # NR, respectively. In the example with a range-1 transmission, or a transmission with a data stream designated as "s", V can be a pre-encoding vector with weights ??,? ... vNl) i, for the base station transmission antenna # 1 to # N1 respectively. In a mode with a range-2 transmission, or a transmission with two data streams si and s2 in the same sub-bearer, V may be a pre-encoding matrix. The matrix H can be the propagation channel matrix between transmission antennas and reception antennas, where hij represents a channel between the transmission antenna j and the reception antenna i. The value n may represent noise and interference by the base station, typically based on the particular channel to the UE or may be specific to UE and may also take into account a preference indicated by EU feedback. Furthermore, the HV matrix can be referred to as the effective channel between a user's data streams and their receivers. The effective channel, instead of the propagation channel H, is all that a UE needs for demodulation purposes. The Precoding weights may or may not be limited to a predefined codebook consisting of a set of predefined vectors or arrays. In a mode with restricted pre-coding, the pre-coding matrix can be signaled by the base unit efficiently with a pre-coding matrix index (PMI), or an index to a pre-coding matrix within a book of predefined codes. The term "matrix" can include the degenerate special case of "vector". In the most generic sense, the term "pre-coding" can refer to any possible transmission scheme that can be considered as mapping a set of data streams to a set of antennas using a matrix V. The term "pre-coding" can include a transmission of "open loop" as a special "pre-coding" with no-weight antennas and any antenna virtualization scheme, such as cyclic delay diversity (CDD).

The pre-coding applied may be based on corresponding feedback from the UE or channel measurements at a base station. In a simple unit schema of a single user base, a DRS set can be defined correspondingly to the effective pre-coded channel (for example, "HV" in the above equation). If two streams are transmitted to a user in a transmission of range 2, then only 2 DRS ports (for example, 2 DRS subsets corresponding to a pre-coded antenna port respectively) are sufficient, even if the current signal transmission can come from all the NT antennas in the base unit where Nt can be greater than 2.

In another method, an effective channel can also be built based on CRS that carry the information of the propagation channel and the pre-coding matrix specifies the user signaled to the UE: As can be seen that one of the differences between DRS and CRS is that the presence of DRS is often known and of interest to a particular EU. Figure 4 illustrates, in a block diagram, a mode of how DRS and CRS can be embedded in an RB. Note that there may or may not be a definition of RB in a frame where RE is assigned to a UE set. The RB 400 shown in Figure 4 may correspond to RB 306 in Figure 3. In particular, the example RB shown in Figure 4 is an RB as defined in the LTE specification. The RB in LTE comprises 12 sub-carriers in frequency and one section in time, where two sections form a "sub-frame", and each section is composed of 7 OFDM symbols in time. CRS displayed on an RB 400 can be divided into several subsets with each associated with a different antenna port. For example, an RB 400 can having a first CRS 404 subset associated with an antenna port # 0 and a second subset CRS 406 associated with an antenna port # 1, respectively with each subset with four positions in a RB 400. In addition, the RB 400 may have a third CRS 408 subset associated with an antenna port # 2 and a fourth subset CRS 410 associated with an antenna port # 3. In addition to any CRS transmitted from the base station 101, additional DRSs may be transmitted within the specific allocation to the UE. The RB 400 may have a set of DRS 412, in this example six DRS 412 associated with a "pre-coded" antenna port # 5. In this case, antenna port # 5, instead of being a current antenna, may correspond to the effective channel seen in device UE 103 after base station 101 applies pre-coding on a set of physical antennas 108. The pre-coding can take the form of beamforming, where a vector of weights can be applied to an antenna to obtain an effective channel.

A DRS pattern (eg, DRS positions and associated reference symbol values) is known to the UE as a predetermined function of some parameters such as cell ID and user ID. · In a traditional operation, once the UE knows all the RS positions as described previously, the EU knows the REs that carry data within its position. The EU will demodulate these ERs that carry data and decode the information directed for it. However, there may be a need for a base station to additionally designate a particular type of RE set within the set of REs allocated for special use. For purposes of convenience in the following description, we also refer to RE of a particular type as "special RE" sometimes. An example of RE of a particular type within an RB is shown in Figure 5. Compared to Figure 4, special REs 520, 521, 522 and 523 are shown. Note that the number of special REs and their position shown in the Figure 5 are only examples for illustration purposes. Of course, the presence of special REs is independent of the presence and pattern of CRS, or DRS or both as shown in Figures 4 and 5. The UE, after receiving such indication corresponding to an RE of a particular type, can treat these special ERs differently from the normal ER data bearers in the data demodulation and decoding process.

Before discussing the use of these REs of a particular type, it should be noted that such an indication corresponding to the RE of a particular type may only be a bit field within the control message received from the station that provides information on the set of RE assigned in a normal operation. Such indication may include the indication of the presence or absence of any particular type of RE. If these special REs are present, the indication may include the positions of at least one RE of a particular type, as well as possibly information about the nature of the special REs so that the UE knows how to handle them.

There are several ways to convert the special RE position information. In one example, information is conveyed as an index to a set of predefined and permissible patterns. In another example, the position information of special REs is indicated by a value representing a relationship with a known pattern. For example, the reference pattern can be cyclically shifted (eg deviated) in frequency or time domain to reach the special RE positions. The known reference pattern can correspond to any RS pattern as long as it is known to the UE. It can be a specific cell pattern RS of a service cell or adjacent cell known to the UE, or a user-specific pattern known to the UE.

Figure 6 is an exemplary flow chart describing the operation of a method according to a modality. In 610, a message is received that provides information of a set of assigned resource elements carrying designated data for a wireless terminal. At 620, an indication corresponding to a resource element of a particular type is received within the set of assigned resource elements. In 630, resource elements that carry data assigned to the wireless terminal are decoded based on the message that provides information and based on the indication.

Figure 7 is an exemplary flow chart demonstrating the operation of a method according to one embodiment. In 710, a set of resource blocks are assigned to a user and a message that provides information of the set of resource elements carrying data addressed to a wireless terminal is transmitted to the wireless terminal. At 720, the set of resource elements of a particular type are determined for a desired mode of transmission, such as multi-unit or multi-point coordinate. At 730, an indication is transmitted corresponding to a resource element of a particular type within the set of assigned resource elements. In 740, a sub-frame is encoded by mapping data modulation symbols with resource elements in the sub-frame based on the indication.

The use case of RE of a particular type is an RE which does not contain any information data symbol assigned to the EU. Therefore, the UE should ignore those special REs during data demodulation and decoding.

This scenario occurs when two or more cells serve the same UE in a coordinated transmission (for example, CoMP as mentioned above). Consider the example of coordinated transmission between two base stations 801, 802 to a single UE 808 as illustrated in Figure 8. Both base stations 801, 802 jointly transmit the same data to UE 808, which is nominally supplied by, say, your service cell base station 801. In this example, the. base station 802 is the coordination station ("or assistant") base from the perspective of UE 808. This advanced operation CoMP may require that base stations 801, 802 have the same data contents addressed to UE 808. But UE 8008 may it does not know the transmission points and therefore, from its perspective, it only assumes normal transmission from the base station 801. As described above, the DRS can make these operations possible as long as the DRSs are sent in the same way as the RE carriers of data. UE 808 knows the DRS pattern if the base station 801 also uses them in the case of non-coordination. UE 808 can assume the same pattern DRS still with coordination, especially given that the coordination is blind to the EU: Meanwhile, the base coordination station 802 may often need to transmit CRS as needed by UE that considers the base station 802 as service cells, with or without coordinated transmission. As mentioned above, the CRS pattern for each cell may be different depending on the cell ID. In the example illustrated in FIG. 8, the CRS positions for the base station 802 is a frequency domain shift or shift of the CRS positions for the base station 801. It can be seen from FIG. data for UE 808 may correspond to a CRS position of the coordination base station 802, which additionally means that, in these REs, the base station 802 may correspond to a CRS position of the base coordination station 802, which additionally means, in these REs, base station 802 can not coordinate transmissions to UE 808 with base station 801 in the same way as other REs. to avoid loss of performance in UE 808, base station 801 and 802 may choose to transmit data only in sets of RE without such conflict. In this case, the base station 801 needs to indicate to UE 808 that these REs that normally carry data are now REs of a particular type, and also in this In this mode, special REs do not contain any information data symbol addressed to UE 808 and therefore should be ignored during data demodulation and decoding.

In another embodiment, the indication corresponding to the resource element of a particular type corresponds to the indication of reference superposition and data symbols in at least one resource element of the particular type. This can be considered as a modification of the previous mode, where the special REs can still carry data symbols addressed to UE 808, except for the fact that these REs will be different from the normal REs carrying data in the sense that the station Base 802 can not coordinate the transmission due to its transmission obligation. Since UE 808 receives signal in these special REs the superposition of information data symbols sent from its service cell 801 and the reference symbols of another base station (cell 802 in this case, but could even be another base station). The indication of these special REs serves the purpose of alerting the UE to potentially process them in a different way from other REs carrying data. For example, the UE may choose to suppress the interference of the superimposed reference symbol before extracting additionally Useful information from special REs.

In the above embodiments, special REs are introduced due to coordinated transmission of more than one base station where a coordination base station is required to transmit its own CRS which may be in a displaced position with respect to the CRS of the service cell . The position of the special RE can easily be indicated as a frequency domain shift (eg deviation) where the offset is with respect to a reference pattern, which corresponds to the CRS positions of the service cell in this case. Of course, if the cell ID of the coordination cell 802 is known to the UE 808, the UE can also derive the special pattern RE. However, it may be more efficient to signal the offset value than to indicate the ID of other cells since typically only limited offset values are possible (for example, 3 corresponding to offset values of 0.1.2 in LTE specifications). The offset value can be, for example, transmitted as an additional field to the downlink information information (DCI) format, which is the control message which is the dynamic control resource allocation information message to a UE. In addition, signal the displacement, due to the small safety margin, it can allow dynamic change between transmission modes that require different configurations of special REs.

The use of special REs is not limited to the previous coordinated transmission cases. In another embodiment, the indication corresponding to the resource element of a particular type corresponds to the indication of a specific reference symbol pattern to a different wireless terminal. Special REs may be useful for transmission of multiple users where a base station transmits different information data symbols to more than one UE in the same set of REs. However, each UE may have different RS. In this way, reference symbols for a UE can be signaled to another UE as special REs.

Figures 9A and 9B are an exemplary illustration of the resource blocks 910, 920, and 930 according to the above embodiment for transmission of multiple users. In this case, if DRS is used, a DRS port can be assigned for each current and each: For example if a transmission of rank 2 is made to each of the two UEs for a total of four transmitted currents, then four DRS ports can be assigned They can be assigned by FDM (frequency division multiplexing or frequency sharing) as in 910 (two UEs with one stream respectively), CDM (Code division multiplexing or code domain sharing) as in 920 (two UEs with one stream respectively) or a combination of FDM and CDM as in 930 (two UEs with two streams respectively). However, each individual UE should have knowledge of DRS ports corresponding to its currents in each case. In the presence of DRS for another UE, additional information from these ports can be useful for the EU.

In one implementation, at 910, data symbols are not assigned to any of the DRS of RE. In this case from the perspective of any UE, the DRSs for the other UEs are indicated as special REs that do not contain data information symbols addressed to that UE: Again, the information of special RE positions can be transmitted as an offset or deviation in relation to the known reference DRS position for that UE.

In a modification of the previous implementation, data is transmitted in special ERs, overlaid with DRS for other users. Specifically, at the DRS positions port 0 for UE 0 illustrated at 910, data may be assigned for UE1. This does not result in significant performance degradation, if the users are spatially separated and the signal energy subsequent to the pre-coding of each user is small when observed by another user This is possible, for example, by channel / feedback status information in the base units, which allows them to choose good user pairs with such separation and good selection of precoding matrices. In such cases, it is also possible that the DRS signals are reinforced with a fixed factor with respect to the data to improve the channel estimate. A UE can take advantage of the knowledge of the position of the RS ports of the other UEs in UE transmission (signaled as special REs), to modify their interference calculations to decode. More specifically, the knowledge of DRS overlap of other users in their data coupled with the signal reinforcement factor can be used to modify interference / variation estimates in these positions. In addition to the special RE positions, with the knowledge of the pilot sequence of other users (usually dependent on the cell ID and a user identifier), one UE may estimate the channel of another UE for interference cancellation.

In one embodiment, REs of a particular type are RE in which there is an absence of any signal transmission from one or more cells. The provision of such special ERs is to allow the EU to "sniff" the interference characteristics.

The concept of indicating RE of a particular type can generally be applied to many other scenarios where there is a need for the EU to be aware of special ERs. For example, it can be used to insert additional RSs. An EU that has the ability to at least ignore special REs can mitigate any potential impact due to future evolution of the standards when special REs are to be developed for special purposes.

In one example, corresponding CRSs for up to 4 antennas are defined in volume 8 of specification 8. When more than 4 antennas are supported in a future version of the LTE specification, some type of RS for each antenna may be required to allow the EU measure the complete spatial characteristic of the channels. They can then be referred to as CSI-RS (as in channel status information), or CQI-RS (Signal quality information), LCRS (low density CRS). For these measurements, in contrast to demodulation, RS can be transmitted less frequently over time. However, when the insertion of new CSI-RSs corresponding to additional or different antennas can be done by converting some normal REs carrying data to special REs, it is still good to signal those REs to avoid any performance impact on demodulation -UE.

In a future version of the specification (LTE-A / Version 10 =, the CRS ports are not necessarily mandatory in each RB.) Furthermore, dedicated LTE-A sub-frames can also be assigned in systems that support version 8 UE, which does not In this case, up to 8 DRS ports can be defined to support up to 8 data streams with eight transmit antennas, these can all be addressed to a single user or multiple users.The different possible patterns with different assignments or number of users, number of streams per user and FDM / CDM can be efficiently assigned to a set of useful patterns representing RE positions of a particular type, for example, data deletion or increased interference or positions to estimate an interference channel, which can index with a pre-defined mapping and signaling as a bit pattern in downstream control signaling.

Claims (20)

NOVELTY OF THE INVENTION, Having described the invention as above, property is claimed as contained in the following: CLAIMS

1. A method for receiving resource allocation in a wireless terminal, comprising: receiving a message that provides information of a set of assigned resource elements carrying data directed to the wireless terminal; receive an indication corresponding to a resource element of a particular type within the set of assigned resource elements; Y decoding resource elements that carry data directed to the wireless terminal based on the message that provides information and based on the indication.

2. The method of claim 1, wherein the set of assigned resource elements corresponds to a set of sub-bearers in one or more symbols in an orthogonal frequency division multiplexing system.

3. The method of claim 1, wherein the indication corresponding to the appeal element of the particular type corresponds to a bit field within the message that provides information on the set of assigned resource elements.

4. The method of claim 1, wherein the element of the particular type is a resource element that does not contain any information data symbol directed to the wireless terminal.

5. The method of claim 1, wherein the indication corresponding to the resource element of the particular type corresponds to the indication of reference overlap and data symbols in at least one resource element of the particular type.

6. The method of claim 1, wherein the indication corresponding to the resource element of the particular type corresponds to the indication of a specific reference symbol pattern to a different wireless terminal.

7. The method of claim 1, wherein the indication corresponding to the resource element of the particular type corresponds to the indication of an absence of signal transmission from one or more cells on at least one resource element of the particular type.

8. The method of claim 1, wherein the The indication corresponding to the resource element of the particular type corresponds to the indication of the absence of any resource element of the particular type.

9. The method of claim 1, wherein the indication corresponding to the resource element of the particular type corresponds to a position of at least one resource element of the particular type.

10. The method of claim 9, wherein the position of the at least one resource element of the particular type is indicated by a value representing a relation to a known reference pattern in the wireless terminal.

11. The method of claim 10, wherein the value representing a relationship with a known reference standard corresponds to a value by which the known reference pattern is shifted in time or frequency domain.

12. The method of claim 10, wherein the known reference pattern corresponds to a specific cell reference symbol pattern of a service cell or adjacent to the wireless terminal.

13. The method of claim 10, wherein the The known reference pattern corresponds to a reference symbol pattern specific to the wireless terminal.

14. The method of claim 1, wherein the corresponding indication with the resource element of the particular type corresponds to an index of a pattern within a set of known patterns for the wireless terminal.

15. A method for signaling mapping of signaling data resource element, comprising: transmitting a message that provides information of a set of data carrying resource elements addressed to a wireless terminal; transmitting an indication in an orthogonal frequency division multiplexing system, wherein the indication corresponds to a resource element of a particular type within the set of resource elements; Y map data modulation symbols to the set of resource elements assigned based on the indication.

16. The method of claim 15, wherein the indication corresponding to the resource element of the particular type corresponds to an indication of resource element that does not contain any information data symbol addressed to the wireless terminal.

17. The method of claim 15, wherein the indication corresponding to the resource element of the particular type corresponds to a position of at least one resource element of the particular type.

18. The method of claim 17, wherein the position of the at least one resource element of the particular type is indicated by a value representing a deviation from a known reference pattern in the wireless terminal.

19. A wireless terminal comprising: a transceiver configured to receive a message that provides information of a set of assigned resource elements carrying data directed to the wireless terminal and configured to receive an indication corresponding to a resource element of a particular type within the set of assigned resource elements; Y a processor coupled to the transceiver, wherein the processor is configured to control operations of the wireless terminal, wherein the processor is configured to decode resource elements carrying data directed to the wireless terminal in based on the message that provides information and based on the indication.

20. The wireless terminal of claim 19, wherein the set of allocated resource elements corresponds to a set of sub-bearers in one or more symbols in an orthogonal frequency division multiplexing system.